JP6173064B2 - Turbocharger with built-in electric machine with permanent magnet - Google Patents

Description

  The present invention relates to the field of electric machines and, more particularly, to a turbocharger comprising a rotating electric machine for use in an internal combustion engine of a motor vehicle.

  Conventionally, an internal combustion engine is equipped with a turbocharger including a turbine driven by the energy of exhaust gas and a compressor integrally connected to the turbine. When the engine speed is low, the turbocharger is assisted by an electric machine.

  As shown in U.S. Pat. No. 6,057,049, one method of providing electrical support for turbocharging is to integrate an electric motor with the turbocharger shaft between the turbine wheel and the compressor wheel. It is. However, this configuration has several drawbacks. More specifically, the added length causes a mechanical problem on the rotor. The added inertia causes turbo lag and reduces the efficiency of the turbocharger. Furthermore, with respect to mechanical / electrical materials (magnets or copper) fixed to the rotor, there are temperature limitations, especially for permanent magnet machines that are sensitive to high temperatures.

U.S. Pat. No. 4,769,993

  The object of the present invention is to provide a preferred electrical machine for a turbocharger that overcomes these drawbacks of the prior art.

  The present invention relates to an electric machine connected to a compressor having a rotating shaft, which forms part of the rotating shaft and is divided by an inclined nonmagnetic portion, and each of the rotating shafts A rotor with two elements of non-magnetic material at the end, and a laminated magnetic iron stack part surrounded by the windings and arranged along the circumference of the rotor to form a first annular gap A stator, an annular body of nonmagnetic material disposed around the stator, and a permanent magnet are disposed around the nonmagnetic annular body and form a second annular gap between the rotor and the rotor. This object is achieved by an electrical machine comprising a housing of magnetic material with a radial wall projecting inwardly towards the rotor.

  In this specific structure, no magnet is used in the rotor of the machine.

  Advantageously, the magnetic and non-magnetic portions of the rotor have similar mechanical and thermal properties.

  Preferably, the stator windings have a single-phase or multi-phase winding configuration in the plurality of slots.

  The element of nonmagnetic material at each end of the rotating shaft may comprise two discs of nonmagnetic material.

  Alternatively, the non-magnetic material element at each end of the rotating shaft may comprise two bearing assemblies of non-magnetic material, such as ceramic bearings.

  Depending on the embodiment considered, the permanent magnet is arranged at the end of the radial wall facing the at least two magnetic parts of the rotor or in a housing around a non-magnetic annulus Arranged.

  The present invention also includes a compressor wheel, a turbine wheel, and a rotating shaft supported by a bearing assembly and connected to the compressor wheel and the turbine wheel, and the rotating shaft is a rotor of the electric machine. It is also related to the turbocharger that is being formed.

  Advantageously, each end of the radial wall forms an internal support for the bearing assembly, the internal support being adapted to support the rotating shaft, the compressor wheel and the turbine wheel as well. It is supported via a nonmagnetic disk having a cylindrical structure.

  According to a specific embodiment, the rotation shaft including at least two magnetic portions divided by the inclined nonmagnetic portion includes an elongated hole along the rotation axis of the rotation shaft, and the nonmagnetic core has the elongated hole. The nonmagnetic core is fixed to the rotary shaft by a nut and a washer made of nonmagnetic material at least at one end of the rotary shaft.

  The inclined nonmagnetic portion may include a nonmagnetic oval washer.

  The present invention is better understood upon consideration of the detailed description below, with illustrative, non-limiting examples relating to the accompanying drawings.

1 is a longitudinal cross-sectional view schematically illustrating an electrically assisted turbocharger, according to one embodiment of the invention. FIG. 6 is a longitudinal cross-sectional view schematically illustrating an electrically assisted turbocharger according to another embodiment of the present invention. 6 is a longitudinal cross-sectional view schematically illustrating an electrically assisted turbocharger, according to yet another embodiment of the invention. FIG. 6 is a longitudinal cross-sectional view schematically illustrating an electrically assisted turbocharger, according to yet another embodiment of the invention. FIG.

  FIG. 1 is a longitudinal sectional view schematically illustrating one embodiment of an electrically assisted turbocharger according to the present invention, preferably for an internal combustion engine.

  Basically, the turbocharger 10 comprises a compressor wheel 12 and a turbine wheel 14 connected together by a common rotating shaft 16 supported in bearing assemblies 18A, 18B. Both the turbine and the compressor may be of any suitable structure known in the art and are therefore only illustrated schematically. For example, the bearing assembly includes two journal bearings or ball bearings mounted at both ends of the shaft. As is known in the art, these ball bearings can be lubricated and cooled by oil passing through an oil passage (not shown).

  According to the present invention, the rotating shaft 16 forming the rotor of the electric machine 20 is made of at least two magnetic materials divided by a nonmagnetic material ramp 24 to avoid any loss of magnetic flux in the bearing assembly. A portion 22A, 22B and two discs 26A, 26B of nonmagnetic material disposed at each end of the rotating shaft are provided.

  These different parts of the rotor are assembled so that they can withstand significant mechanical stresses, especially at very high peripheral speeds. Furthermore, it is necessary to deal with differences in thermal expansion between materials. However, advantageously, both materials are similar in thermal and mechanical properties. For some time, hot isostatic pressing (HIP) can be used for this purpose, i.e. all magnetic and non-magnetic parts are inserted into the sheath, and this assembly is placed in the HIP container at high pressure and high temperature. Is put in. Next, the rotor part is integrally fitted by diffusion welding.

  The electric machine further includes a stator that includes a laminated magnetic iron stack portion 28 that is surrounded by the windings 30 and disposed along the periphery of the rotor so as to form a first radial annular gap 32. The stator windings must have a single-phase or multi-phase winding configuration in a plurality of slots. A ring 34 of nonmagnetic material is disposed around the stator.

  A magnetic material housing 40 is disposed around a ring of non-magnetic material. The housing includes radial wall portions 40A and 40B, and the radial wall portions 40A and 40B have a second diameter between the end portions of the wall portions that receive the permanent magnet 36 and the outer periphery of the rotor. By forming the directional annular gap 42, it protrudes inward toward the rotor.

  The position of the permanent magnets at the ends of the radial walls 40A, 40B facing the at least two magnetic parts of the rotor (and thus close to the second annular gap 42) is not essential, and It is important to note that a position within the enclosure 40 surrounding the stator is also possible, as shown in FIG.

  In the embodiment of FIG. 2, the end of the radial wall portion of the housing 40 forms an internal support for the bearing assembly portions 18 </ b> A and 18 </ b> B that support the rotating shaft 16. More specifically, as illustrated, the bearing assemblies 18A, 18B, according to this embodiment, are non-magnetic discs having a cylindrical structure adapted to also support compressor and turbine wheels. Support directly.

  The operation of the turbocharger is well known and will not be described in detail. Traditionally, the turbine wheel 14 has been rotated at high speed by the energy of the exhaust gas, so that the common shaft 16 can also rotate the compressor wheel 12 to introduce air into the engine cylinder. However, when such a turbocharger includes the electric machine 20 as in the present invention, the operation thereof is different and changes depending on whether the electric machine functions as a motor or a generator.

  When the rotating shaft 16 rotates at high speed (this is the case of normal operation of the engine), the rotor that forms part of this shaft also rotates at high speed. This rotation of the rotor of the electric machine (operating with the generator) generates a magnetic field with magnetic flux lines extending radially through the first annular gap 32 around the rotor. This change in magnetic flux induces an electromotive force in the stator, which is extracted from the stator winding 30 and supplied to various loads, for example, storage batteries via a rectifier bridge (not shown). Is generated.

  When the rotating shaft 16 rotates at a low speed, that is, when the flow of exhaust gas is small (for example, particularly during engine start-up), the electric machine is operated as a motor so that the compressor can be rotated faster. Can do. In fact, the stator creates a rotating magnetic field in the first annular gap 32 thanks to an alternating current supply (not shown) connected to the stator winding 30. At the same time, a DC magnetic field created by the permanent magnet 36 flows through the magnetic circuit 40 and intersects the second annular gap 42. However, since the rotor is formed of three parts, the magnetic flux generated on one side 22A of the rotor in the rotating shaft 16 is caused by the nonmagnetic shielding of the shaft (the central inclined portion 24 and the disks 26A and 26B). Therefore, it cannot continue to flow in the rotor. Thus, the magnetic flux is intersected with the first annular gap 32, forced to enter the stator following the conventional magnetic flux of the stack 28, and returns to the rotor (at the other side 22B). The flux circuit is closed through the magnetic housing 40, the flux returns to the left-hand side of the rotor, and creates two conventional poles in the rotor, and the rotation of the rotor allows the poles to rotate.

  While preferred embodiments have been shown and described, it should be understood that some variations and modifications may be made in the embodiments without departing from the scope of the invention. More specifically, when an electrical machine is illustrated as operating with a turbocharger, it is clear that such a machine can be incorporated, for example, in a mobile compressor or mobile centrifugal compressor. .

  The discs 26A and 26B of nonmagnetic material used in the embodiment of FIGS. 1 and 2 can be omitted when the bearing assemblies 18A and 18B are made of a nonmagnetic material such as a ceramic bearing.

  This is illustrated in FIG. 3, corresponding to the embodiment of FIG. 2, if not omitted, but this solution using non-magnetic bearing assemblies 18A, 18B should be applied to the embodiment of FIG. You can also.

  FIG. 4 shows an example of a possible method for assembling the rotating elements of a turbocharger according to the invention.

  The rotating shaft 16 including at least two magnetic portions 22A and 22B divided by the inclined nonmagnetic portion 24 includes an elongated hole along the rotating axis of the rotating shaft 16. A core 60 or tie rod formed from a non-magnetic material such as aluminum is inserted into the elongated hole, and the non-magnetic core 60 is at least at one end of the rotating shaft by a nut 61 and a washer 62 of non-magnetic material. Fixed to the rotating shaft. In the example of FIG. 4, a nut 61 and a washer 62 of nonmagnetic material are used at each end of the tie rod 60 to make the nonmagnetic tie rod 60 integral with the wheels 12, 14.

  The inclined portion 24 having the through hole may be configured by a washer made of a nonmagnetic material.

  The assembly method disclosed with reference to FIG. 4 may be used in combination with any of the embodiments described with reference to FIGS. An alternative to avoiding the implementation of hydrostatic compression molding.

DESCRIPTION OF SYMBOLS 10 Turbocharger 12 Compressor wheel 14 Turbine wheel 16 Rotating shaft 18A Bearing assembly part 18B Bearing assembly part 20 Electric machine 22A Magnetic part 22B Magnetic part 24 Inclined (nonmagnetic) part 26A Disc 26B Disc 28 Laminated magnetic iron stack part 30 Winding 32 First annular gap 34 Ring 36 Permanent magnet 40 Housing 40A Radial wall 40B Radial wall 42 Second annular gap 60 Core, tie rod 61 Nut 62 Washer

Claims (12)

An electric machine (20) connected to a compressor (12) comprising a rotating shaft (16),
A rotor forming a part of and the rotational shaft with an axis of rotation, at least two magnetic portions divided by the non-magnetic portion inclined (24) (22A, 22B) , and each end of said rotary shaft A rotor with two elements of non-magnetic material in the section;
A stator comprising a laminated magnetic iron stack portion (28) surrounded by the winding (30) and arranged along the periphery of the rotor to form a first annular gap (32);
A ring (34) of non-magnetic material disposed around the stator;
A radial direction comprising a permanent magnet (36), arranged around the ring and projecting inward toward the rotor by forming a second annular gap (42) with the rotor A magnetic material housing (40) with walls (40A, 40B);
Equipped with,
The rotational axis (16) comprises an elongated hole along the rotational axis, and a non-magnetic core (60) is inserted into the elongated hole;
The non-magnetic core (60) is fixed to the rotating shaft at two ends of the rotating shaft by a nut (61) and a washer (62) made of nonmagnetic material .   The electric machine according to claim 1, wherein the element of non-magnetic material at each end of the rotating shaft comprises two disks (26A, 26B) of non-magnetic material.   The electric machine according to claim 1, wherein the element of non-magnetic material at each end of the rotating shaft comprises two bearing assemblies (18A, 18B) of non-magnetic material.   The electric machine according to any one of claims 1 to 3, wherein the magnetic part and the non-magnetic part of the rotor have similar mechanical and thermal characteristics.   The electric machine according to any one of claims 1 to 4, wherein the winding (30) of the stator has a single-phase or multi-phase winding configuration in a plurality of slots.   The said permanent magnet (36) is arrange | positioned at the edge part of the said radial direction wall part (40A, 40B) facing the said at least 2 magnetic part (22A, 22B) of the said rotor. The electric machine according to any one of the above.   The electric machine according to any one of the preceding claims, wherein the permanent magnet (36) is arranged in the housing (40) around the non-magnetic ring (34). A compressor wheel (12);
A turbine wheel (14);
A rotating shaft (16) supported by a bearing assembly (18A, 18B) and connected to the compressor wheel and the turbine wheel, the rotating shaft having a rotating axis and a rotor of an electric machine (20) And the rotor comprises at least two magnetic parts (22A, 22B) divided by an inclined non-magnetic part (24) and two elements (26A) of non-magnetic material at each end of the rotating shaft , 26B; 18A, 18B)
Comprising
The electric machine is
A stator comprising a laminated magnetic iron stack portion (28) surrounded by the winding (30) and arranged along the periphery of the rotor to form a first annular gap (32);
A ring (34) of non-magnetic material disposed around the stator;
A permanent magnet (36) disposed around the non-magnetic annulus and projecting inward toward the rotor by forming a second annular gap (42) with the rotor; A magnetic material housing (40) with radial walls (40A, 40B);
Further comprising a,
The rotational axis (16) comprises an elongated hole along the rotational axis, and a non-magnetic core (60) is inserted into the elongated hole;
The nonmagnetic core (60) is a turbocharger (10) fixed to the rotating shaft by a nut (61) and a washer (62) made of nonmagnetic material at two ends of the rotating shaft .   The turbocharger according to claim 8, wherein the magnetic part and the non-magnetic part of the rotor have similar mechanical and thermal characteristics.   The turbocharger according to claim 8, wherein the winding (30) of the stator has a single-phase or multi-phase winding configuration in a plurality of slots.   Each end of the radial wall forms an internal support for the bearing assembly, the internal support having a cylindrical structure adapted to also support the compressor wheel and the turbine wheel. The turbocharger according to claim 8, wherein the rotating shaft is supported through the nonmagnetic element. The turbocharger according to claim 8 , wherein the inclined nonmagnetic part (24) comprises a nonmagnetic oval washer.

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